The invention relates to an aqueous firm cream and a process for impregnating or priming mineral building materials to impact water-repellency.
Organosilicon compounds are used in building protection especially owing to their outstanding impregnation effect for protection from water and dirt. Siliconates, silicone resins, monomeric silanes and oligomeric silanes have been established for years for this application. The active ingredients are usually dissolved or dispersed in low-viscosity carrier media, such as, for example, organic solvents or water. Low-viscosity active ingredients, such as, for example, monomeric silanes or low-viscosity mixtures of silanes and siloxanes, can also be applied undiluted to the building material.
A disadvantage of these impregnating compositions is that they readily run off or drip off vertical surfaces and very particularly during overhead work.
Silane-, siloxane- or silicone resin-based compositions containing mineral thickeners can on the other hand also be applied as a relatively thick layer to the building materials, without running off. The organosilicon compound penetrates into the building material and the thickener remains behind. U.S. Pat. No. 4,076,868 describes, for example, solutions of methylpolysiloxane in toluene which are thickened with silica. WO 95/25706 describes a process for imparting water-repellency with solvent-free silane/siloxane mixtures thickened with bentonites. The disadvantage of these processes is that the mineral thickener remains behind on the building material and has to be removed and disposed of.
In EP-A-819 665, these disadvantages are counteracted by using so-called water-repellent creams. These are aqueous, firm products based on organosilicon compounds, which are free of solids and organic solvents. The active ingredient content of these creams is preferably 60 to 95%.
On absorptive building materials, such as, for example, bricks, concrete, sand-lime bricks, fibre cement boards, mineral renders and many natural stones, impregnating compositions whose active ingredient content is frequently in the range of 5-25% are generally applied. For these applications, the active ingredient concentration of the water-repellent creams described in EP-A-819 665 is too high.
It was the object of the present invention to provide water-repellent creams whose application includes all advantages of the water-repellent creams of EP-A819 665 but whose active ingredient content can additionally be adjusted as desired.
The invention relates to an aqueous, firm cream which contains the components
(A) which are selected from
(A1) C1-C20-alkyl-C2-C6-alkoxysilanes and
(A2) organopolysiloxane containing alkoxy groups,
(C) emulsifier and
(D) organic solvent.
In a preferred embodiment, the aqueous cream additionally contains a component (B) which contains aminoalkyl groups and is selected from alkoxysilane (B1) containing aminoalkyl groups or organopolysiloxane (B2) which, in addition to other organosiloxane units, contains those siloxane units which have radicals bonded via SiC and having basic nitrogen, with the proviso that the amine number of the organopolysiloxane (B2) is at least 0.01.
Pasty, water-containing formulations which are emulsion systems comprising water-immiscible oil phase, namely active ingredients (A) and optionally (B) plus organic solvents (D), water and emulsifiers (C), are designated as cream. The cream is considered to be firm if it can be applied by means of a doctor blade or brush or by spraying in a coat thickness of at least 0.5 mm to vertical absorptive mineral building materials, such as, for example, sand-lime brick or clay brick, and, after application, does not run down more than 1 cm before it has been completely absorbed by the building material.
Preferably, the C1-C20-alkyl-C2-C6-alkoxysilanes (A1) have 1 or 2 identical or different, optionally halogen-substituted monovalent C1-C20-alkyl radicals bonded via SiC, and the remaining radicals are identical or different C2-C6-alkoxy radicals. Methoxysilanes undergo hydrolysis too rapidly and prevent a sufficient shelf life.
Examples of the C1-C20-alkyl radicals are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl and tert-pentyl radicals; hexyl radicals, such as the n-hexyl radical; heptyl radicals, such as the n-heptyl radical; octyl radicals, such as the n-octyl radical, and isooctyl radicals, such as the 2,2,4-trimethylpentyl radical; nonyl radicals, such as the n-nonyl radical; decyl radicals, such as the n-decyl radical and dodecyl radicals, such as the n-dodecyl radical; cycloalkyl radicals, such as cyclopentyl, cyclohexyl, 4-ethylcyclohexyl and cycloheptyl radicals, norbornyl radicals and methylcyclohexyl radicals.
Examples of halogen-substituted C1-C20-alkyl radicals are alkyl radicals substituted by fluorine, chlorine, bromine and iodine atoms, such as the 3,3,3-trifluoro n-propyl radical, the 2,2,2,2xe2x80x2,2xe2x80x2,2xe2x80x2-hexafluoroiso-propyl radical and the heptafluoroisopropyl radical.
The unsubstituted C1-C12-alkyl radicals are particularly preferred.
Examples of C2-C6-alkoxy radicals are the ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy and tert-butoxy radicals; pentyloxy radicals, such as the n-pentyloxy radical, and hexyloxy radicals, such as the n-hexyloxy radical. The ethoxy radicals are particularly preferred.
The alkoxy radicals may be substituted by halogen atoms, but this is not preferred.
The aqueous cream may contain an organopolysiloxane (A2) containing alkoxy groups, or a mixture of several organopolysiloxanes. The organopolysiloxanes may additionally contain hydroxyl groups, which facilitate binding to the building materials.
The organopolysiloxanes (A2) preferably have a viscosity of not more than 2000 MPa.s, in order to achieve a particularly good distribution on the pore surfaces in the masonry. It is also possible to use organopolysiloxanes having a higher viscosity, including solid resins, e.g. solid methylsilicone resins having a molecular weight of 2000 to 10,000 g/mol with, for example, a glass transition temperature range of 40-50xc2x0 C., or solid resins comprising R3SiO0.5 and SiO2 units (MQ resins) having a preferred ratio of R3SiO0.5 to SiO2 of 0.4:1 to 1.2:1. These are preferably present in solution in silanes (A1) or in low-viscosity organopolysiloxanes (A2) or in the organic solvent (D).
The organopolysiloxanes (A2) comprising units of the general formula (I)                               R          x                ⁢                              Si            ⁡                          (                              OR                1                            )                                y                ⁢                              Si            ⁡                          (              OH              )                                z                ⁢                  O                                    4              -              x              -              y              -              z                        2                                              (        I        )            
in which
R denote identical or different monovalent, optionally halogen-substituted C1-C20-hydrocarbon radicals bonded via SiC,
R1 denote identical or different monovalent C1-C6alkyl radicals,
x denotes 0, 1, 2 or 3, on average 0.8 to 1.8,
y denotes 0, 1, 2 or 3, on average 0.01 to 2.0, and
z denotes 0, 1, 2 or 3, on average 0.0 to 0.5, with the proviso that the sum of x, y and z is not more than 3.5, are particularly suitable.
Examples of the C1-C20-hydrocarbon radicals are the C1-C20-alkyl radicals and halogen-substituted C1-C20-alkyl radicals mentioned above in the case of the organoalkoxysilanes (A1), the alkenyl radicals, such as the vinyl, allyl, n-5-hexenyl, 4-vinylcyclohexyl and 3-norbornenyl radicals; aryl radicals, such as the phenyl, biphenylyl, naphthyl, anthryl and phenanthryl radicals; alkaryl radicals, such as o-, m- and p-tolyl radicals, xylyl radicals and ethylpheyl radicals; aralkyl radicals, such as the benzyl radical, the alpha- and the xcex2-phenylethyl radical. The unsubstituted C1-C12-alkyl radicals and the phenyl radical are particularly preferred.
Although not indicated in the abovementioned formula, some of the radicals R can be replaced by hydrogen atoms bonded directly to silicon atoms. However, this is not preferred.
Examples of the radicals R1 are the methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl and tert-butyl radicals; pentyl radicals, such as the n-pentyl radical, and hexyl radicals, such as the n-hexyl radical, the methyl and ethyl radicals being particularly preferred.
Preferably, x has an average value of 0.9 to 1.2. Preferably, y has a value of 0.01 to 1.2. Preferably, z has an average value of 0.0 to 0.2.
Examples of organosiloxanes (A2) are those which are obtainable by reacting methyltrichlorosilane and optionally a C1-C8-alkyltrichlorosilane and optionally dimethyldichlorosilane or phenyltrichlorosilane with methanol or ethanol in water, such as the organopolysiloxanes of the empirical formulae
CH3Si(OC2H5)0.8O1.1,
C6H5Si(OC2H5)0.72O1.14,
(CH3)0.7(iso-octyl)0.3(OCH3)0.6SiO1.2,
CH3(OC2H5)0.02SiO1.49 or
(CH3)1.2(OC2H5)0.02SiO1.39 
The alkoxysilanes (B1) optionally used in addition to component (A) and containing aminoalkyl groups are preferably C1-C6-alkoxysilanes (B1) and have in particular the general formula (II)
R2uR3vSi(OR4)4-u-vxe2x80x83xe2x80x83(II),
in which R2, R3 and R4 have the meanings mentioned below in the case of the general formula (III) and
u is 0, 1 or 2 and
v is 1, 2 or 3,
with the proviso that the sum of u and v is less than or equal to 3.
An example of a preferred alkoxysilane (B1) is H2N (CH2)2NH (CH2)3xe2x80x94Si(OCH3)3.
The organopolysiloxanes (B2) optionally used in addition to component (A) are preferably those comprising units of the general formula (III)                                           R            a            2                    ⁢                                                    R                b                3                            ⁡                              (                                  OR                  4                                )                                      c                    ⁢          Si          ⁢                      xe2x80x83                    ⁢                      O                                          4                -                a                -                b                -                c                            2                                      ,                            (        III        )            
in which
R2 denotes identical or different monovalent, optionally halogen-substituted, SiC-bonded C1-C20-hydrocarbon radicals free of basic nitrogen,
R3 denotes identical or different monovalent, optionally halogen-substituted, SiC-bonded C1-C30-hydrocarbon radicals having basic nitrogen,
R4 may be identical or different and denotes a hydrogen atom or C1-C6-alkyl radicals,
a denotes 0, 1, 2 or 3,
b denotes 0, 1, 2 or 3, on average at least 0.05, and
c denotes 0, 1, 2 or 3,
with the proviso that the sum of a, b and c is less than or equal to 3 and that the amine number of the organopolysiloxane (B2) is at least 0.01.
The amine number designates the number of ml of 1 N HCl which are required for neutralizing 1 g of organopoly-siloxane (B2). The amine number of the organopolysiloxane (B2) is preferably at least 0.1, in particular at least 0.2, and preferably not more than 8, in particular not more than 4.
Examples and preferred examples of the radical R2 are mentioned above in the case of radical R. In particular, the methyl and the isooctyl radical are preferred.
Preferably, a hydrocarbon radical, in particular a methyl radical, is also bonded to each silicon atom to which a hydrogen atom is bonded.
Radical R3 is preferably a radical of the general formula (IV)
R52NR6xe2x80x94xe2x80x83xe2x80x83(IV),
in which
R5 may be identical or different and denotes hydrogen or a monovalent, optionally substituted C1-C10-hydrocarbon radical or C1-C10-amino-hydrocarbon radical and
R6 denotes a divalent C1-C15-hydrocarbon radical.
Examples of the radical R5 are the examples of hydrocarbon radicals given for radical R, and hydrocarbon radicals substituted by amino groups, such as aminoalkyl radicals, the aminoethyl radical being particularly preferred.
Preferably, at least one hydrogen atom is bonded to each nitrogen atom in the radicals of the general formula (IV).
Radical R6 is preferably a divalent hydrocarbon radical having 1 to 10 carbon atoms, particularly preferably 1 to 4 carbon atoms, in particular the n-propylene radical.
Examples of radical R6 are the methylene, ethylene, propylene, butylene, cyclohexylene, octadecylene, phenylene and butenylene radical.
Preferred examples of radicals R3 are
H2N(CH2)3xe2x80x94,
H2N(CH2)2NH(CH2)2xe2x80x94,
H2N(CH2)2NH(CH2)3xe2x80x94,
H2N(CH2)2xe2x80x94,
H3CNH(CH2)3xe2x80x94,
C2H5NH(CH2)3xe2x80x94,
H3CNH(CH2)2xe2x80x94,
C2H5NH(CH2)2xe2x80x94,
H2N(CH2)4xe2x80x94,
H2N(CH2)5xe2x80x94,
H(NHCH2CH2)3xe2x80x94,
C4H9NH(CH2)2NH(CH2)2xe2x80x94,
cyclo-C6H11NH(CH2)3xe2x80x94,
cyclo-C6H11NH(CH2)2xe2x80x94,
(CH3)2N(CH2)3xe2x80x94,
(CH3)2N(CH2)2xe2x80x94,
(C2H5)2N(CH2)3xe2x80x94 and
(C2H5)2N(CH2)2xe2x80x94.
The examples of alkyl radicals R1 are also fully applicable to the radical R6.
Examples and preferred examples of the radical R4 are mentioned above in the case of radical R1. In particular, the methyl and the ethyl radical are preferred.
The preferred average value for a is 0 to 2, in particular 0 to 1.8.
The preferred average value for b is 0.1 to 0.6, in particular 0.15 to 0.30.
The preferred average value for c is 0 t6 0.8, in particular 0.01 to 0.6.
Preferably, the organopolysiloxanes (B2) have a viscosity of 5 to 5000, in particular of 100 to 3000, mPa.s at 25xc2x0 C.
Organopolysiloxanes (B2) can be prepared in a known manner, for example by equilibration or condensation of silanes having amino functional groups with organpolysiloxanes which contain alkoxy groups and/or hydroxyl groups and which are free of basic nitrogen.
The aqueous creams contain an emulsifier (C) known per se.
Particularly suitable anionic emulsifiers are:
1. Alkylsulphates, particularly those having a chain length of 8 to 18 C atoms, alkyl- and alkarylether-sulphates having 8 to 18 C atoms in the hydrophobic radical and 1 to 14 ethylene oxide (EO) or propylene oxide (PO) units.
2. Sulphonates, in particular alkylsulphonates having 8 to 18 C atoms, alkylarylsulphonates having 8 to 18 C atoms, taurides, esters and monoesters of sulphosuccinic acid with monohydric alcohols or alkylphenols having 4 to 15 C atoms; these alcohols or alkylphenols may also be optionally ethoxylated with 1 to 40 EO units.
3. Alkali metal and ammonium salts of carboxylic acids having 8 to 20 C atoms in the alkyl, aryl, alkaryl or aralkyl radical.
4. Partial phosphoric acid esters and their alkali metal and ammonium salts, in particular alkyl and alkaryl phosphates having 8 to 20 C atoms in the organic radical, alkyl ether phosphates or alkaryl ether phosphates having 8 to 20 C atoms in the alkyl or alkaryl radical and 1 to 40 EO units.
Particularly suitable nonionic emulsifiers are:
5. Polyvinyl alcohol which also contains 5 to 50%, preferably 8 to 20%, of vinyl acetate units, having a degree of polymerization of 500 to 3000.
6. Alkyl polyglycol ethers, preferably those having 8 to 40 EO units and alkyl radicals of 8 to 20 C atoms.
7. Alkylaryl polyglycol ethers, preferably those having 8 to 40 EO units and 8 to 20 C atoms in the alkyl and aryl radicals.
8. Ethylene oxide/propylene oxide (EO/PO) block copolymers, preferably those having 8 to 40 EO and PO units.
9. Adducts of alkylamines having alkyl radicals of 8 to 22 C atoms with ethylene oxide or propylene oxide.
10. Fatty acids having 6 to 24 C atoms.
11. Alkylpolyglycosides of the general formula with the proviso that the sum of u and v is less than or equal to 3. Rxe2x80x94Oxe2x80x94Zo, in which R* denotes a linear or branched, saturated or unsaturated alkyl radical having on average 8 to 24 C atoms and Zo denotes an oligoglycoside radical with on average O=1-10 hexose or pentose units or mixtures thereof.
12. Natural substances and their derivatives, such as lecithin, lanolin, saponins, cellulose; cellulose alkyl ethers and carboxyalkylcelluloses whose alkyl groups each have up to 4 carbon atoms.
13. Linear organo(poly)siloxanes containing polar groups, in particular those having alkoxy groups of up to 24 C atoms and/or up to 40 EO and/or PO groups.
Particularly suitable cationic emulsifiers are:
14. Salts of primary, secondary and tertiary fatty amines having 8 to 24 C atoms with acetic acid, sulphuric acid, hydrochloric acid or phosphoric acids.
15. Quaternary alkyl- and alkylbenzeneammonium salts, in particular those whose alkyl groups have 6 to 24 C atoms, in particular the halides, sulphates, phosphates and acetates.
16. Alkylpyridinium, alkylimidazolinium and alkyl-oxazolinium salts, in particular those whose alkyl chain has up to 18 C atoms, especially the halides, sulphates, phosphates and acetates.
Particularly suitable ampholytic emulsifiers are:
17. Amino acids having long-chain substituents, such as N-alkyldi(aminoethyl)glycine or salts of N-alkyl-2-aminopropionic acid.
18. Betaines, such as N-(3-acylamidopropyl)-N,N-dimethylammonium salts having a C8-C18-acyl radical and alkylimidazolium betaines.
Preferred emulsifiers are nonionic emulsifiers, in particular the alkyl polyglycol ethers mentioned above under 6., the adducts of alkylamines with ethylene oxide or propylene oxide which are mentioned under 9., the alkylpolyglycosides mentioned under 11. and the polyvinyl alcohol mentioned under 5. Particularly preferred polyvinyl alcohols still contain 5 to 20%, in particular 10 to 15%, of vinyl acetate units and preferably have a degree of polymerization of 500 to 3000, in particular of 1200 to 2000.
In order to establish any desired active ingredient content, the aqueous creams contain, as component (D), a water-immiscible organic solvent which preferably has a solubility of at most less than 1% by weight in water at 20xc2x0 C. and preferably has a boiling point of 60 to 280xc2x0 C. Suitable organic solvents (D) are, for example, alkanes having boiling points preferably in the range from 60 to 280xc2x0 C., particularly preferably 90 to 220xc2x0 C., aromatic hydrocarbons, such as toluene, xylenes, trimethylbenzenes and tetramethylbenzenes, chloro-hydrocarbons, such as trichloroethylene or 1,1,1-trichloropropane, ketones, esters, such as n- or tert-butyl acetate, relatively long-chain alcohols, such as hexanols, heptanols or octanols, and relatively long-chain ethers, such as di-n-octyl ether. Owing to their low odour, alkanes, dearomatized or petroleum hydrocarbons and isoparaffins having boiling points in the range from 100 to 220xc2x0 C. are particularly preferred.
The water-repellent creams described in EP-A-819 665 also have the disadvantage that, particularly in the case of very absorptive building materials of low alkalinity, such as, for example, clay bricks, poor water-repellency is produced directly at the surface of the building material.
The aqueous creams according to the invention may contain, as an additive, finely divided silicas (E) which have been rendered water-repellent and which further improve the water-repellency of the surfaces, also of absorptive surfaces of low alkalinity. In fact, the silicas (E) accumulate at the surface of the building material. In this way, considerable water-repellency is obtained very rapidly after impregnation. Suitable silicas (E) are obtainable, for example, if silica obtained by flame hydrolysis or precipitation is rendered water-repellent with organosilicon compounds, in particular silanes. The silicas (E) preferably have a specific surface area of at least 40 m2/g, particularly preferably at least 60 m2/g.
Hydrophobic solids cannot be emulsified in the water-repellent creams disclosed in EP-A-819 665, since the creamy consistency is destroyed as a result.
The total amount of the active ingredient components (A) and (B) in the aqueous creams is preferably 1 to 80% by weight, in particular 2 to 70% by weight.
The amount of the component (B) in the aqueous creams is preferably 0.1 to 20% by weight, in particular 0.2 to 10% by weight.
The amount of the emulsifier (C) in the aqueous creams is preferably 0.1 to 10% by weight, in particular 0.2 to 5% by weight.
The content of organic solvent (D) in the aqueous cream is preferably 1 to 95% by weight, in particular 5 to 80% by weight.
The content of silicas (E) in the aqueous creams is preferably 0.01 to 4% by weight, in particular 0.01 to 2% by weight.
The aqueous creams may also contain buffer substances which stabilize the pH in the range from 5 to 8, in which the alkyltrialkoxysilanes are very resistant to hydrolysis. All organic and inorganic acids and bases which are chemically inert to the other components of the emulsions, in particular the alkali metal, alkaline earth metal and ammonium salts of carboxylic acids, phosphoric acid, carbonic acid and sulphuric acid, are suitable. Sodium carbonate, sodium bicarbonate, sodium hydrogen phosphate and a mixture of acetic acid and aqueous ammonia solution are particularly preferred. The amount of buffer substances is preferably not more than 3, in particular 1, % by weight of the total amount of the creams.
The aqueous creams may also contain additives for improving the water-repellency, for example metal soaps, such as stearates or oleates.
In addition to the components described above, the aqueous creams may contain fungicides, bactericides, algicides, microbicides, odour substances, corrosion inhibitors and antifoams as additives. The preferred amount of additives is not more than 2, in particular 0.5, % by weight of the total amount of the creams.
The aqueous creams are prepared by conventional methods for the preparation of aqueous creams.
For this purpose, one possibility is initially to prepare a cream from the components (A), (B) and (C) by a process described in EP-A-819 665. Organic solvent (D) is then stirred into said cream in an amount sufficient to give the desired active ingredient content.
In a further preferred process, the components (A), (B) and (D) are premixed and are slowly emulsified in the aqueous solution of the emulsifier (C) until a creamy consistency is achieved.
Also preferred is a process in which the components (A) and (B) are premixed with only some of the total amount of the component (C) and emulsified in the water-emulsifier mixture until a creamy consistency is obtained. Finally, the amount of solvent (D) still remaining is then stirred into the creamy emulsion.
If solid resins comprising R3SiO0.5 and SiO2 units are used, these are dissolved in the silanes (A1) or in the solvent (D) before preparation of the cream according to the invention.
The preparation of the aqueous creams according to the invention is preferably carried out in pressure emulsifiers, colloid mills or in particular in a high-speed stator-rotor stirring apparatus according to Prof. P. Willems. If a further solvent (D) is added to a cream which has already been prepared, said solvent is preferably stirred in without extreme application of shear force, in order to avoid destroying the stiff emulsion phase producing the creamy consistency.
The aqueous creams are particularly suitable for the water-repellent impregnation and priming of mineral building materials, such as natural or artificial stone, concrete and reinforced concrete, cellular concrete, sand-lime bricks, clay bricks, clinker, marble or granite.
The aqueous creams are particularly suitable for imparting water-repellency to mineral-bound, preferably cement-bound, fibre building materials whose fibres consist of natural fibres or manmade fibres. Suitable natural fibres are mineral fibres, such as rock wool, quartz fibres or ceramic fibres, or vegetable fibres, such as cellulose. Suitable manmade fibres are, for example, glass fibres, plastics fibres and carbon fibres. The use of the aqueous cream for imparting water-repellency to cement-bound cellulose fibre components is particularly preferred. The cellulose fibres may be, for example, jute, coconut or hemp fibres or may originate from paper, cardboard or waste paper.
The aqueous creams are preferably applied to the building material by spraying, brushing, rolling or trowelling. The coat thickness is preferably 0.05 to 3 mm, particularly preferably 0.1 to 2 mm.
In the following examples, all stated parts and percentages relate to weight, unless stated otherwise. Unless stated otherwise, the following examples are carried out at a pressure of the ambient atmosphere, i.e. at about 0.10 MPa, and at room temperature, i.e. at about 20xc2x0 C., or at a temperature which is established on combining the reactants at room temperature without additional heating or cooling. The active ingredient content of the aqueous creams is defined as the sum of all organosilicon components.